Thermoacoustic heat engine (TAHE) converts thermal power (heat) into acoustic power. TAHE has been gaining significant interest because of its non-fuel specific, low cost and high reliability (due to reduced moving parts) compared to conventional IC engines. The performance of TAHE depends upon the various parameters such as stack position, stack length and resonator length. Previously, we built a fixed TAHE which converts heat energy to electrical energy with an efficiency of 2 %. However, the performance of the fixed engine was not fully optimized. To investigate further, another novel tunable TAHE has been built with the goal of optimizing the efficiency by tuning three critical parameters, namely stack position, stack length and resonator length. This paper shows the influence of stack parameters (stack position and stack length) and resonator length on the performance of the thermoacoustic heat engine. The performance is measured in terms of the pressure amplitude generated inside the TAHE using air as the working fluid. It is observed that the stack's position considerably affects the performance. Further, from experiments, it is observed that the maximum acoustic power is generated when the stack is positioned closer to a pressure antinode. © 2014 IEEE.